With Kesari’s philosophy in mind, researchers at the University of Exeter and Kings College London are conducting a massive, online study.

Its purpose is to measure essential brain functions in healthy people aged 50 or older.

The researchers collected data from more than 17,000 people, making this one of the largest studies of its kind.

In particular, the data analyzed in the Exeter study used tests to determine whether humans can maintain brain health by performing certain repeatable activities.

The researchers suggest that this is indeed the case when it comes to measuring the speed of grammatical reasoning and accuracy of short-term memory.

They determined that by habitually working on word puzzles older adults are able to keep their brains functioning at levels up to 10 years younger than their actual age.

Use it or lose it

Kesari, a neuro-oncologist, and chair of the Department of Translational Neuro-oncology and Neurotherapeutics at the John Wayne Cancer Institute at Providence Saint John’s Health Center in California, spoke with Healthline about general brain health.

He suggested that the more you use the different parts of your brain, the stronger the connections get between what’s being exercised and the parts of the brain responsible for those activities.

“When you don’t use your brain very much, it gets weaker,” Kesari told Healthline. “I think it is important for brain health that you use your brain more.”

The Exeter study supports Kesari’s assertions.

“We found direct relationships between the frequency of word puzzle use and the speed and accuracy of performance on nine cognitive tasks assessing a range of aspects of function including attention, reasoning, and memory,” said Keith Wesnes, professor of Cognitive Neuroscience at the University of Exeter Medical School, in an article on Exeter's website.

Wesnes continued, “Performance was consistently better in those who reported engaging in puzzles, and generally improved incrementally with the frequency of puzzle use.”

Joshua Grill, PhD, co-director of UCI MIND and an associate professor of psychiatry and human behavior, said association studies [like the Exeter study] are valuable and important for hypothesis generation.”

However, he told Healthline, “they’re not instructive to neurologists writing a prescription to tell their older patients who are concerned about developing cognitive problems to do so many crossword puzzles per week.”

Keeping our brains healthy

Grill said, “For the last several years there’s been a strong interest in the increasingly clear relationship between how we act and treat our bodies and our brains throughout life and the risk of developing cognitive problems later in life.”

“As much as half of the risk for developing Alzheimer's disease and late life cognitive problems could be due to lifestyle choices and behaviors,” he continued. “And whether we engage in cognitive activities like puzzles is very much on that list.”

Grill admits that we still have a way to go before we learn all the answers, but he is still a big supporter of cognitive activities like doing word puzzles.

“When in your life you engage in these behaviors, what behaviors we can and should engage in, and how much of those behaviors we can and should engage in to maximize the reduction in risk, all remain open questions,” he said.

Studies linking intellectually stimulating activities to cognitive function are not new. However, what makes the Exeter study so unique is its sheer size.

Dr. Howard Fillit, founding executive director and chief science officer of the Alzheimer's Drug Discovery Foundation pointed out that, “One large clinical trial known as the ACTIVE study reported that playing a specific type of brain training game reduced the risk of developing dementia.”

The ACTIVE study used a game that Fillit said “trained ‘speed-of-processing,’ which was designed to improve the speed and accuracy of a person’s visual attention.”

“You can think of the aging brain like an old computer,” said Fillit. “Speed-of-processing tasks help the aging brain perform more like a new computer by training it to process visual information more quickly.”

“And this,” he continued, “may help stem cognitive decline.”

Alzheimer's disease and dementia

In discussing cognitive decline in the older brain, the conversation often turns to the subjects of dementia and Alzheimer’s disease.

The Alzheimer's Association defines dementia as “a general term for a decline in mental ability severe enough to interfere with daily life.”

Dementia is not a specific disease. It describes a life-altering decline in thinking skills.

“Alzheimer’s is the most common type of dementia,” the association website says. “[It] causes problems with memory, thinking, and behavior. Symptoms usually develop slowly and get worse over time, becoming severe enough to interfere with daily tasks.”

The association noted that Alzheimer’s accounts for 60 to 80 percent of dementia cases.

“If the way we live our lives is responsible for up to half of our risk for getting Alzheimer's and cognitive problems later in life, then the other half of the risk is due to genetics,” said Grill.

Despite that, he said that given the number of genes that can affect someone’s risk of getting Alzheimer’s, “The recommendations we make really do not differ depending upon someone’s genes.”

Taking charge of your brain health

Experts at the National Institute on Aging agree that some of the most important things you can do each day to promote cognitive health are to eat healthy foods, be physically active, exercise your mind, and stay socially connected.

In addition, since all brains with Alzheimer’s contain amyloid plaques, are there things we can do to slow or stop them from forming?

Reduce inflammation

“Focusing on modifiable risk factors such as hypertension, diabetes, cholesterol, cardiovascular risk factors, essentially are probably one of the most important things for delaying aging in the brain whether it’s related to amyloid or not,” said Kesari.

He went on to say, “We think a lot of diseases are caused by inflammation. So, low inflammation diets? Can anti-inflammatories help in the long run? These are unanswered questions.”

Kesari suggested that, “Inflammation is one of the causes of many, all the diseases we deal with, including cancer, and that [controlling it somehow] whether it’s eating, lifestyle, etc., would probably delay onset of neurological disorders.”

He said it is not a proven thing, but that it makes sense.

“Some preliminary research suggests,” added Fillit, “that maintaining a healthy weight, exercising regularly, and eating a healthy diet rich in omega-3 fatty acids such as DHA are associated with lower levels of beta-amyloid plaques and tau tangles in the brain.

Healthy heart, healthy brain

Grill pointed out the importance of a healthy heart.

“Some [research data] suggests that reducing cardiac risk factors in the middle adult years is just as, or even more important than, the types of genes you carry for risk of developing amyloid plaques later in life.”

“Many of us believe that there’s no more significant risk factor for getting Alzheimer’s than the presence of amyloid plaques in the brain,” said Grill.

“So,” he continued, “if you’re in your 40s and 50s and you smoke and you don’t exercise and your diet isn’t the healthiest in the world, changing two of the three of those could be more impactful than changing your genes, if you were able, to the risk for developing amyloid plaques later in life.”

Counting sheep

“Make sure you get a good night’s sleep,” Grill insisted.

He explained, “It’s pretty clear that when we sleep we clean our brain of metabolic by-products and even some toxins, and that includes cleaning our brain of the amyloid protein that accumulates in those amyloid plaques.”

This is because when you sleep, cerebrospinal fluid moves through the brain, acting as a flushing mechanism.

“Getting a good night’s sleeps does seem to be critical for lowering our risk for developing these problems later in life,” said Grill.

Fillit agreed.

“Establishing a bedtime routine and maintaining a regular sleep schedule can be helpful. Seven to eight hours of sleep per night is recommended,” he said.

Buyer beware

Certainly, the subject of brain health is ripe for exploitation by hucksters with unsubstantiated sales gimmicks and promises.

Fillit warns, “Keep in mind that not all brain games are created equal and some manufacturers have been sued for making unsubstantiated claims.”

Scientists themselves admit that in order to determine the effectiveness of word puzzle-type interventions on cognitive health, they still need to undertake randomized control studies.

Researchers have shown that there are certain activities that can help keep brains healthy as we age. Yet, as Grill maintains, “No one can [yet] make a claim that if you do x, y, z you're certain to not develop cognitive problems.”